High Resolution peripheral QCT (HRpQCT) enables the detection of erosions less than 0.5 mm in width or depth at metacarpo-phalangeal (MCP) joints. Using 3-D high resolution analysis of cortical bone erosions, this one is also able to evaluate the volumes of erosion and the evolution under treatments IL6 (6- interleukin) plays a major role in inflammatory process and bone damages related to RA. Tocilizumab (TCZ) is a humanized anti-IL-6R monoclonal antibody, developed and investigated in several clinical trials in RA. This biotherapy, in association with methotrexate (MTX) or given in monotherapy, is efficient in RA with inadequate response to MTX or anti-TNF b (tumor necrosis factor). TCZ reduces dramatically systemic inflammation, structural progression and improves clinical symptoms and quality of life.